A militia has shelled Tripoli airport, destroying several planes parked there, a Libyan government spokesman said, as heavy fighting between armed groups prompted the United Nations to pull its staff out of the North African country.

At least 15 people have been killed in clashes in Tripoli and the eastern city of Benghazi since Sunday, and a Libyan official said several Grad rockets hit Tripoli International Airport late yesterday, damaging the control tower.

Government spokesman Ahmed Lamine said several planes parked at the airport were destroyed. The Libya Herald said they included a $250 million Afriqiyah Airways Airbus A330. Another of the airline's planes was damaged.

Air Malta has not operated flights to Tripoli since Sunday. Flights to Benghazi were stopped in May. All airspace in Western Libya, including that over Misrata, has now been closed by air traffic controllers, at least until tomorrow, and the only functioning main airport in the country is now that at Labraq, near Beida.

Lamine sad the Libyan government had studied the possibility to bring international forces to enhance security.

Three years after the fall of Muammar Gaddafi, Libya has slipped deeper into chaos with its weak government and new army unable to control brigades of former rebel fighters and militias who often battle for political and economic power.

Seven people were killed in Tripoli on Sunday in the worst fighting for six months in the capital, where rival militias have been fighting for control of the airport.

Security and medical sources said at least six people had been killed and 25 wounded in Benghazi in heavy fighting between security forces and rival militias since late Sunday.

The UN mission in Libya said the closure of Tripoli airport and the deteriorating security situation made it impossible for it to operate.

In Benghazi, irregular forces loyal to renegade former general Khalifa Haftar bombarded Islamist militia bases as part of his campaign to oust militants. Special forces clashed with militia fighters in the city.

Most of the dead and wounded were civilians, according to security and medical sources at Benghazi hospital. At least 10 houses were hit with missiles, and government offices and banks were forced to close.